Prior art drill collet mechanisms typically grasp removable burs with frictional, magnetic, or latch engagement schemes. The inventor of the instant application is the inventor of U.S. Pat. No. 4,378,212 which describes a magnetic system for holding detachable burs and also describes, in some detail, about a dozen other pertinent prior art patents. U.S. Pat. No. 4,378,212, its teachings, and the prior art referred to therein, are hereby incorporated by reference into this application.
Surgeons, particularly neurosurgeons, prefer a drill with as small a diameter as possible in order to ease access to very small and delicate areas. However, the apparatus needed inside the drill to permit a variety of drill burs to be easily and quickly inserted and removed from the drill necessitates larger diameter drills. The prior art designs referred to above are less than satisfactory in this respect. The present invention provides an unusually compact arrangement wherein burs are solidly locked in place, for rotation of the drill in either direction, while still allowing quick and easy removal and maintaining a very narrow diameter drill.